Grinding machine



April 13, 1954 A. SILVEN ET AL GRINDING MACHINE 6 Sheets Sllheet l oa vQ n 'i NEQQ v &

Filed May '7, 1952 Q WK u b Qkm mean.

A TTor-ney NR EE Om p WMA 1 A5 TT RR M wk H55 H WH IIIIHEN II MN awn NR r L Mu 9mm l April 1954 H. A. SILVEN ET AL 4,831

GRINDING MACHINE Filed May 7, 1952 6 Sheets-Sheet 2 i 76e 76!) I 119 137 d I39 76 7 '76 777 i 76C 7627 65/ l I I I 0 i I L InvenTor-s HERBERT A. SIM/EN STEWART 5'. MADER Afforne) April 13, 1954 H. A. SILVEN ETAL 2,674,831

GRINDING MACHINE Filed May '7, 1952 6 Sheets-Sheet 3 a2 21 a4 2a B I'nveTlfOrS HERBERT A. EILVEN STEWART 5'. MAE/5R B April 13, 1954 H. AJSILVEN ETAL 2,674,831

GRINDING MACHINE Filed May 7, 1952 s SheetsSheet 5 I II 24 .28 v 7 26 I84 I83 I 9 z I69 I68 5 I 6 7 I57 4 I I E I66 I44 I44 I65 Inve-n rs 167a HERBERT A. SILVEN STEWART 5. MADER w I HE. E M AHor-ney April 13, 1954 H. A. SILVEN ET AL 2,674,831

G'RINDING MACHINE Filed May 7, 1952 e Sheets-Sheet s- M vs .InvenTor-s HERBERT. A. SILVEN VYSTEWART 5'. MAJJER V l l wforney Patented Apr. 13, 1954 2,674, 31 GRINDING MACHINE Herbert A. Silven and Stewart S. Mader, Worcester, Mass, assignors to Norton Company,

Worcester, Mass, a c

setts orporation of Massachu- Application May 7, 1952, Serial No. 286,472

8 Claims.

This invention relates to grinding machines, r

and more particularly to a grinding wheel speed control device automatically to maintain a uniform peripheral speed of the grinding wheel.

One object of the invention is to provide a simple and thoroughly practical grinding wheel speed control mechanism automatically to maintain a substantially constant peripheral speed on the grinding wheel as it wears away. Another object is to provide an automatically actuated V-belt wheel driving mechanism for varying the speed of rotation of a grinding wheel spindle so as to maintain a substantially constant peripheral speed of the wheel as it wears away. Another object is to provide an automatically actuated mounting for the wheel driving motor arranged to facilitate varying the distance between the axis of the motor shaft and the wheel spindle so as to vary the speed of the spindle. Another object is to provide a driving connection between the truing tool feeding mechanism and the motor mount actuating mechanism automatically to increase the speed of the Wheel spindle so as to maintain a substantially constant peripheral speed of the grinding wheel as it wears away. Other objects will be in part obvious or in part pointed out hereinafter.

In the accompanying drawings in which is shown one of the various possible embodiments of the mechanical features of the invention;

Figure 1 is a fragmentary side elevation of a grinding machine, showing the grinding wheel driving mechanism, the truing apparatus, and the driving connection for adjusting the speed of rotation of the grinding wheel;

Figure 2 is a vertical sectional view, on an enlarged scale, of the truing apparatus feeding mechanism, and the driving connection for adjusting the speed control;

Figure 3 is a fragmentary rear elevation, on an enlarged scale of the parts shown in Figure 1;

Figure 4 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 4-4 of Figure 5, of the mechanism for adjusting the position of the wheel driving motor to facilitate varying the speed of rotation of the grinding wheel;

Figure 5 is a horizontal sectional view, taken approximately on the line 5-5 of Figure 4, showing the mechanism for adjusting the position of the wheel driving motor;

Figure 6 is a fragmentary sectional view taken approximately on the line 6-6 of Figure 5;

Figure 7 is a vertical sectional view, taken approximately on the line 1-1 of Figure 5, through the motor supporting platen;

2 Figure 8 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 8-8 of Figure 7, through one of the roller supports for the motor platen;

Figure 9 is a cross sectional view on an enlarged scale, taken approximately on the line 9-9 of Figure 1, through the variable speed motor pulley;

Figure 10 is a cross sectional view, through a modified variable speed motor pulley; and

Figure 11 is a combined hydraulic and electrical diagram of the actuating mechanism and the controls therefor.

A grinding machine has been illustrated in drawings comprising a base II) which serves as a support for a rotatable work support (not shown). The base II] serves as a support for a transversely movable wheel slide II which is arranged to slide transversely on V-way I2 and fiatway I3 on the upper surface of the base I0.

A suitable feeding mechanism is provided for causing a transverse feeding movement of the wheel slide II relative to the base I0 comprising a half nut I4 depending from the under side of the wheel slide II. The half nut I4 meshes with or engages a rotatable feed screw I5 which is rotatably supported by the base Ill. The feed screw I5 may be actuated by any of the well known conventional feeding mechanisms. The feeding mechanism above described serves to facilitate a tranverse feeding movement of the grinding wheel I! to grind a rotatably mounted cylindrical work piece I9. The work piece I9 is supported for rotation by a conventional type head stock and foot stock (not shown), such as, for example that shown in the expired U. S. patent to C. H. Norton No. 762,838, dated June 14, 1904, to which reference may be had for details of disclosure not contained herein.

The Wheel slide II serves as a support for a rotatable wheel spindle I6 which is journalled in spaced bearings (not shown). The spindle It supports a grinding wheel IT on its left hand end, (Fig. 2). The grinding wheel I! is partially surrounded by a wheel guard I8 which is adjustably fastened to the wheel slide I I.

The wheel spindle H3 and grinding wheel I! are driven by an electric motor 20 which is mounted on a transversely adjustable platen 2| supported by dovetailed slide-ways formed on the upper surface of a motor base 23. The motor base 23 is adjustably mounted on the upper surface of the wheel slide II by means of a plurality of screws 24, 25, 26 and 21 which pass through elongated slots 28, 29, 30 and 3| formed in the motor base 23 and are screw threaded into the wheel slide I I.

'A roller support is provided between the motor base 23 and the platen 2| comprising a plurality of rollers 32, 33, 34, and 35 each is supported by horizontally arranged studs 38, 31, 38 and 38 respectively. A plurality of rollers 48 and M are supported by the platen 2| and rotate on a plurality of studs 42,43,44 and 45 respectively which are arranged-so that'their axes are parallel with the dovetailed surface of the slide-way 22.

The platen is arranged so that it may be adjusted automatically relative to the wheel slide H to facilitate adjusting the position'of the motor 28 so as to vary the speed ofqthewhfiel spindle l6 and the grindinglwheel llina manner to be hereinafter described. The motor base 23 supports a rotatable member 58 having a cam 51 formed in its upper plane face. The member is supported by spaced antifriction bearings 52 and 53 which are carried by the motor base 23. The platen 2| is provided with a vertically arranged; downwardly projecting stud 54 having, a follower roller 55 rotatably supported on its lower end which rides within the cam 51. A driving mechanism is provided for the member 5i! comprising aworm gear 56 formed integrally therewith. The worm gear 55 meshes, with a worm 51 whichv is mounted on: a horizontally arranged rotatable shaft 53 (Fig. 5). The shaft 53, isjournalled in spaced bearings bland Bil oarried by the motor base 23.

A driving mechanism is provided between a motor shaft 65 on the motor, 28 and. the wheel spindle it which is arranged so that the speed of the wheel spindle. It may be automatically varied to maintain at substantially constant peripheral speed .on the grinding wheel 11 .as it isreduced in diameter due towheel wear and successive, truing operations. This driving mechanism maycornprise an automatic variable pitch motor pulleyi 86,: such. as, manufactured by AlliseChalmers MfgCo, under U. S. Patent No. 2,262, 97 to E. Otto et al. "dated November 11, 1941, to which reference may be had for details of disclosures not contained herein. The pulleymay be a multipleiv-groove pulley 66, as shown in Fig. 9Vcomprising avplurality of pulley flanges 81, 81a, 81b and- 610 which are keyed together by means of atie-rod-Gd which is carried by a sleeve 69. A plurality of pulley flanges 78, ma, WI) and 10c are slidably mounted on the sleeve69 and held together by means of a tie-rod H. The pulley flanges 61 and T0 are arranged to form a plurality of variable V-grooves' 12, 12a, 12b and 120. A plurality of compression springs 13, 13a and 13b are interposed between pulley flanges inc-41 Mb-81b and Illa-61c to facilitate movement of the flanges to vary the size of the V-grooves 12, 12a, 12b and 120. The pulley 66- isconnected by multiple V-belts 14' with a multiple V-groove pulley 15 mounted on the end of the wheel spindle l6. Asillustrated in the drawings, the motor supporting platen 2! is shown ina rearward position so thatthe pulley grooves 52, 72a, and 12b and IZcare expandedso that the V-belt M rides in the grooves adjacent to the bottom thereof. It will be readily apparent that as the motor platen 2! is adjusted toward the wheel spindle in a manner to be hereinafter discussed, the center distance between the motor shaft 65. and the wheel spindle It will be shortened thereby allowing the compression springs 13a and 13b to expand thereby reducing the size of the V-grooves 72, 72a 12b and He so that the drivin be ts r d h eh rn i the ti r ve e e y increasing the effective diameter of v the driving 4 pulley 86 to increase rotative speed of the grinding wheel spindle l6 and the grinding wheel FL This movement may continue until the V-belts M ride within the grooves adjacent to the outer eriphery of the pulley flanges 81 and 10.

If desired a single V-belt drive may be utilized comprising a single V-groove pulley '56 which is mounted on the motor shaft 65 (Fig. 10). This pulley may be a Roto-Cone variable pitch motor pulley, such as manufactured by Gerbing Mfg. Corp. of Northbrook, Illinois, under U; Sp Patents No. 2,475,954 and No. 2,475,955 to W. E Gerbing dated July 12, 1949 to which reference may be had for details of disclosure not contained herein. The pulley l6 may cornprisea pair of pulley flanges 18a and 166 which are slidably mounted on a sleeve its supported by the motorshaft 65. The flanges Hid and 7812 have inner frustoconical surfaces 36d forming a V-groove which is engaged by a single Vi-belt ltc. The pulley flanges 15 and 7527 are arranged to move toward and from each other to vary the size of the V-groove 16d. A rack bar it) is fixedly connected to the pulley flange 550:. A rack bar 15g is connected to the pulley flange 16b. The rack bars 76) and 16g meshwith a gear 16h which, is rotatably supported by a stud. 16k carried by the sleeve 160. A compression spring "Him is interposed between a flange i811 carried by the sleeve 78c and hub portion of the pulley flange b. It will be readily apparent from the foregoing disclosure that as the center distance is changed between the motor shaft 65 and the wheel spindle 16, the compression of the spring 76m will serve through the mechanism above described to simultaneously adjust the position of the pulley flanges lta and 181). As illustrated in the draw ings the single V -belt 16a is riding at the bottom of the V-groove 16d when the motor platen. 21 is in a rearward position. As the motor platen 25 is adjusted transversely toward the wheel spindle, the compression of the spring 18m Will serve to decrease the size of the V-groove 7617 so that the V-belt 18c rides higher in the v-groove thereby increasing the speed of rotation of the wheel spindle I8 and the grinding wheel l1.

Wheel guard i8 serves as a support for a housing 88 having an upper plane surface which supports a bracket M. The bracket Si is arranged to support a grinding wheel truing apparatus. A slide base 82 is fixedly supported on the bracket 8i by means of a plurality of clamping screws 83 and 84. The slide base 82 serves as a support for longitudinally traversable slide 85 which is arranged to slide longitudinally on a dovetailed slide-way 88 formed on the slide base 82.

A hydraulically operated mechanism is provided for traversing the slide 85 longitudinally comprising a hydraulic cylinder 81 which contains a slidably mounted piston 88. The piston 88 is connected to thel-eft hand end of a piston rod 89 (Fig. 11), the other 'end of which is fastened to an end cap 98 fixedly mounted on the end of the longitudinally movable slide 85. A pair of nuts 9| serve to lock the piston rod 89 to the end cap )90. The end cap 9d carries an adjustable stop screw 92. which is arranged in the path of the end ofthecylinder 8'! to facilitate limiting movement of :,the slide- 85 toward the left. When fluid ,under pressure is passed through a pipe 85,-, into. a cylinderchamber 96, the piston 88 together-with slide 85 will be moved throttle valve 5 toward the right (Fig. 11). During thismovement of the piston 88, fluid within a cylinder chamber 98 may exhaust through a pipe 91.

A suitable control mechanism is provided for controlling the admission to and exhaust of fluid from the cylinder 81 comprising a rotary type reversing valve I having a valve rotor IOI which may be manually actuated by a control lever I02. When fluid under pressure is passed through a pipe I13 from a motor driven fluid pump I10, it passes into a valve chamber I03, through a traverse passage I04 formed in the valve rotor IOI into a valve chamber I and through the pipe 91 into the cylinder chamber 98 to cause the piston 88 to move toward the left (Fig. 11). This movement of the piston 88 and the slide 85 toward the left continues until the stop screw 02 engages the right hand end of the cylinder 81. During movement of the piston 88 toward the left fluid within the cylinder chamber 96 may exhaust through the pipe 95 into a valve chamber I00,- through a transverse passage I01 in the valve rotor I 0!, into a valve chamber I08 and out through an exhaust pipe I09 and through a IIO. By manipulating of the throttle I I0, the speed of movement of the piston 08 and the longitudinally movable slide 85 may be readily varied as desired.

When it is desired to reverse the direction of the movement of the slide 85 and the piston 88,

the control lever I02 is moved in a clockwise direction into the dotted line position I02a (Fig. 11) which movement shifts the valve rotor so that fluid under pressure from the pipe I13 passes into the valve chamber I06, through the pipe 05 into the cylinder chamber 90 to move the piston 88 and the slide 85 toward the right. During this movement fluid within the cylinder chamber '98 may exhaust through the pipe 91 into the valve chamber I05, through the passage I04 into the valve chamber I03 and out through the exhaust pipe I09 and the throttle valve H0.

The longitudinally movable slide 85 serves as a support for a vertically arranged housing H4. The housing I I4 is provided with a pair of spaced bearings H5 and H6 which support a vertically arranged truing tool carrier II1 having a truing tool II8 mounted at its lower end.

A suitable feeding mechanism is provided for feeding the carrier I I1 vertically in either direction relative to the slide 85. This mechanism may comprise a nut and screw feeding mechanism in which a screw threaded portion H9 is provided on the carrier II1. A rotatable nut I meshes with or engages the threaded portion I I9. The nut I20 is provided with an integral flange I2I which is rotatably supported on the housing II4 by a pair of plates I22 and I23.

A manually operable feed wheel I25 is mounted on the lower end of a vertically arranged rotatable shaft I20 which is rotatably supported within a housing I21. The housing I21 is fixedly mounted relative to the housing I I4. The upper end of the shaft I26 is provided with a pinion I28 which meshes with a gear I29 keyed on the outer periphery of the nut I20. It will be readily apparent from the foregoing disclosure that a rotary motion of the hand wheel I25 will be imparted through the mechanism above described to rotate the nut I20 and thereby impart a vertical movement to the truing tool carrier II1 and the truing tool H8. The direction of movement of the hand wheel I25 serves to determine the direction of the movement of the carrier II1.

In order to attain one of the main objects of the 6. invention; it is desirable to actuate the cam 5| automatically by and in timed relation with the operating mechanisms of the machine to increase the rotative speed of the grinding wheel I1so as to maintain the peripheral face thereof at a substantial uniform speed as the wheel wearsaway due to wheel wear and truing. In the pre-- ferred form, the cam 5I is preferably connected to be actuated by and in timed relation with the truing apparatus feeding mechanism. As illustrated in the drawings a beveled gear I3 0 is keyed to the nut I20. The beveled gear I30 meshes with a beveled gear I31 which is carried by a rotatable shaft I38. tatably mounted in a housing I38 and is connected to one end of a flexible driving shaft I40. The other end of the flexible driving shaft I40 is connected to a rotatable shaft I4I which is journalled in spaced bearings I43 and supported within a housing I44. The housing I44 is supported on the rear end of the wheel slide I I. The shaft I4! carries a beveled gear I45 (Fig. 4) which meshes with a beveled gear I40 which is keyed on the left hand end of a shaft I54. The

shaft I 54 is in turn keyed to the right hand end of the worm shaft 58. It will be readily apparent from the foregoing disclosure that when the feed wheel I25 is rotated to cause a down feeding movement of the truing tool carrier II1 and a truing toool H8, a rotary motion will be imparted to the cam 5I through the mechanism above described to cause a transverse movement of the motor platen 2| relative to the wheel slide II. The transverse movement of the platen 2| serves to shorten the distance between the axis of the motor shaft 65 and the axis of the wheel spindle I8 thereby allowing the released compression of the springs within the pulley B0 to narrow the V-grooves 12 of the pulley and thereby cause the V-belts 14 to ride upon a larger diameter of the grooves 12 so as to increase the rotative speed of the wheel spindle I6 to maintain a substantially uniform peripheral speed on the grinding wheel I1 as it wears away.

' After the wheel I1 has been worn to a predetermined smaller diameter, however, it is necessary to replace the wheel with a larger diameter wheel and at the same time to reset both the truing tool I I8 and the platen 2I into their initial positions. This is preferably accompanied by means of a fluid pressure actuated mechanism comprising a fluid motor I50 mounted on the rear end of the wheel slide II. The fluid motor I50 is provided with a drive shaft I5I which has a worm I52 keyed thereon. The worm I52 meshes with a worm gear I53 rotatably mounted on a shaft I54 which is keyed to the worm shaft 58. The worm gear I53 has a clutch member I55 fixedly mounted thereon. A clutch member I55 is slidably keyed on the shaft I54 and is arranged so that it may be thrown into or out of engagement with the clutch member I55. A clutch shift lever I51 is pivotally mounted on a stud I58 carried by the housing I44. The clutch lever I51 is provided with a pin I59 which rides in a groove I60 formed in the periphery of the clutch member I56. It will be readily apparent from the foregoing disclosure that when the clutch shift lever I51 (Fig. 5) is rocked in a clockwise direction, the clutch member I50 will be moved into engagement with the clutch memher I 55 so that a rotary motion of the fluid motor The shaft I30 is ro-' assess:

wise direction (Fig. to move the platen- 2i rearwardly to its initial position.

A hydraulically operated-1 mechanism is pro.- vided for actuating: the clutch lever I51 comprising a cylinder I6I which contains: a slidably mounted piston I62. Thev piston IE2 is provided with a piston rod I63. A compression spring I64 serves normally to hold the piston I92 in the position illustrated in Fig. 5 with the clutch member I56 disengaged. The piston rod I63 supports a slidably mounted sleeve I85v which is provided with an annular groove I66. The left hand end of theclutch lever I51 is yoke shaped and is provided with a pair of diametrically opposed, studs I61 and I61a (Fig. 6).

When fluid under pressure is admitted through a pipe I58 into. a cylinder chamber I99; the piston IE2 is moved upwardly-(Fig 5) against the compression of the spring IE4 to rock the clutch lever I51 in a, clockwise direction so as to engage the clutch member I56 with the clutch member I55.

A fluid pressure system is provided for supplying fluid under pressure comprising the motor driven fluid pump I19 which draws fluid through a pipe Ill from a reservoir I12 and passes fluid under pressure through the pipe I13 through the control valve I99 above described and also to a control valve I14 for controlling the admission of fluid to the cylinder ISI. A pressure relief valve I15 is connected in the pipe line I13 to facilitate maintaining the desired operating pressure within the fluid pressure system. The control valve I14 is a piston type valve comprising a valve stem I79 having a pair of spaced valve pistons I11 and I18 formed integrally therewith. A compression spring I19 normally holds the valve stem I16 ina right hand end position as illustrated in Fig. 11. A solenoid I82 is provided for shifting the valve stem I13 toward the left to admit fluid. under pressure to the cylinder IGI. When the solenoid I82 is energized, the valve stem- I16 moves toward the left against the compression of the spring I19 so that fluid under pressure from the pipe I13 enters a valve chamber I89 formed between the valve pistons I11 and I18 and passes through the pipe I68 into the cylinder chamber I69 to engage the clutch members I59-I55 in a manner above described.

The cylinder I9I and piston I62 serve as a sequence valve to control the admission of the fluid to the fluid motor i59. When fluid under pressurev is passed through the pipe I58 into the cylinder chamber I69 to cause an upward movement of the piston IGI (Fig. 11), the piston ISI gradually uncovers a port I93 after which fluid under pressure may pass through a pipe I84 to start the fluid motor I59. Fluid exhausts from the motor I59 through a pipe I85 and a throttle valve I89 which controls the rate of rotation thereof.

An electrical control apparatus is provided comprising power lines I88. A start switch I99 serves to close a circuit to energize a relay switch I99. When the start switch I89 is closed, it serves to close the relay switch I99 and. thereby to energize thesolenoid I82 to shift the valve H4 so as to admit fluid under pressure to the cylinder chamber I69. A normally closed limit switch I92 is arranged so that its actuated plunger I93 lies in the path of movement of the motor platen 2I. When the motor platen 2I is in an extreme rearward position, the switch I92 is opened. The switch I92 serves as a safety device to deenergize the relay switch I99 and thereby to deenergize the solenoid; I82; when. the motor platen 2] reaches. a: rearward position so;-as to. disengage the clutch I 5B-:- -I55; and thereafter: to stop the fluid motor I59.

Thev operation of this improved speed controlled mechanism will be readily apparent from the foregoing disclosure. Assuming a full size grinding wheel I1 is mounted on the wheel spindle It, the grinding operation proceeds until the grinding wheel I1 requires truing. During this initial operation the grinding wheel I1 is rotated at a maxmum speed. When the grinding wheel requires ;truing, the feed wheel I25 is rotated to cause a downfee ding movement of the diamond or truing tool- II'8 after which the control lever I92 is manipulated to cause a longitudinal movement of the slide 85 to; traverse the truing tool II8 across. the peripheral face of-the grinding wheel I1. The truing, tool may be passed as many times as desired across the periphery of the-grinding wheel I1 and the diamond feed downwardly before each traversing movement by manipulation of the hahdwheel I25. As above described, the rotary motion of the feed nut I29 will be imparted through the flexible shaft I99 to impart a rotary motion to the cam 5I so as to cause a transverse movement of the motor platen 21 thereby changing the center distance between the motor shaft 65 and the wheel spindle Is to increase the rotary speed of the wheel spindle IE to maintain a substantially constant peripheral speed on the grinding Wheel I1. After the grinding wheel has beencom-v pletely worn out and requires replacement, the truing tool I39 is reset and the motor platen 2I moved rearwardly toits initial position by actuation of the start switch I89 to first engage the clutch members I59I55 thereafter to start the fluid motor I59 so as to rotate the worm 51, the worm gear 56 and the cam ill in the reverse direction tocause a rearward movement of the motor platen 2I. During the rearward movement of the platen 2|, as it approaches its rearward position, an adjustable screw 299 (Fig. 5) on the platen 2| engages'the forward end of the piston rod I63 and shifts it rearwardly so that the piston I62 gradually closes the port I83. Gradual closing of the port I83 serves gradually to cut-ofi the flow of fluid to the motor I59 so as to gradually slow-down the motor I59, and alsoto disengage the clutch I55-I56 at the same time the platen 2| engages and actuates the limit switch I92 to stop the platen 2I in its rearward or initial position. The resettingmovement of the truing tool H8 and the motor platen 21 may be stopped at any position desired by manipulation of the stop switch I9I.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successively achieved. As many possible em.- bodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawings is to be interpreted as illustrative and" not ina limiting sense.

We claim:

1. In a-grinding machine having a transversely movable wheel slide, a rotatablewheel spindle thereon, a grinding wheel on said spindle, an electric motor adjustably mounted on said wheel slide, a variable speed .V-belt drive between said .9 motor and. wheel spindle including a V-groove variable pitch automatic pulley on said motor, a V-belt groove pulley on said spindle, a V-belt connected therebetween, means including a cam and follower mechanism interposed between said motor and wheel slide to facilitate adjustment of said motor relative to the said slide so as to vary the center distance between the motor and the wheel spindle and thereby to vary the speed of the grinding wheel, a wheel truing apparatus on said slide including a longitudinally movable slide, a transversely movable carrier on said longitudinal slide, a truing tool thereon, a feeding mechanism interposed between said longitudinal slide and said carrier for feeding the truing tool toward and from the grinding wheel, and operative driving connections between the truing tool feeding mechanism and the cam mechanism whereby actuation of the said mechanism automatically actuates said ram to adjust the position of the motor relative to the wheel slide so as to vary the speed of the wheel spindle to maintain a substantially constant peripheral speed of the grinding wheel as it wears away.

2. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, a slidably mounted platen on said wheel slide, an electric motor on said platen, a variable speed V-belt drive between said motor and wheel spindle including a V-groove variable pitch automatic pulley on said motor, a V-pulley on said spindle, a V-belt connected therebetween, means including a cam and a follower interposed between said platen and wheel slide to facilitate adjusting said platen relative to said slide so as to vary the center distance between the motor and wheel spindle and thereby to vary the speed of the grinding wheel, a truing apparatus on said slide including a longitudinally movable slide, a transversely movable carrier on said slide, a truing tool thereon, a feeding mechanism interposed between said longitudinal slide and carrier for feeding the truing tool toward and from the grinding wheel, and operative driving connections between the truing tool feeding mechanism and the cam mechanism whereby actuation of the truing tool feeding mechanism automatically actuates said cam to adjust the position of the motor platen relative to the wheel slide so as to vary the speed of the spindle to maintain a substantially constant peripheral speed of the grinding wheel as it wears away.

3. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, a slidably mounted platen on said wheel slide, an electric motor on said platen, a variable speed V-belt drive between said motor and wheel spindle including a V-groove variable pitch automatic pulley on said motor, a V-groove pulley on said spindle, a v-belt connected therebetween, means including a rotatable cam and a follower interposed between said platen and wheel slide to facilitate adjustment of said platen relative to the wheel slide so as to vary the speed of the grinding wheel, a wheel truing apparatus on said slide including a longitudinally movable slide, a transversely movable carrier thereon, a truing tool on said carrier, a feeding mechanism including a rotatable nut and a feed screw interposed between said slide and carrier for feeding the truing tool toward and from the grinding wheel, a flexible shaft, operative connections between one end of said shaft and said rotatable nut, and

operative connections between the other end of said shaft and the cam mechanism whereby actuation of the feeding mechanism automatically actuates said cam to adj t the p n of he motor platen relative to the wheel slide so as to vary the speed of the wheel spindle to maintain a substantially constant peripheral speed of the grinding wheel as it wears away.

i. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, a slidably mounted platen on said wheel slide, an electric motor on said platen, a variable speed multiple V-belt drive between said motor and spindle including a multiple V-groove variable pitch automatic pulley on said motor, a multiple V-groove pulley on said spindle, multiple V-belts connected therebetween, means including a rotatable cam and a follower interposed between said platen and wheel slide to facilitate adjustment of said platen relative to the slide so as to vary the speed of the grinding wheel, a wheel truing apparatus on said slide including a longitudinally movable slide, a transversely movable carrier on said longitudinal slide, a truing tool thereon, a nut and screw feeding mechanism ineluding a rotatable nut interposed between said slide and carrier for feeding the truing tool toward and from the grinding wheel, a flexible shaft, operative connections between the rotatable nut and said shaft and operative connections between the other end of said shaft and said cam whereby actuation of the feeding mechanism automatically actuates said cam so as to adjust the position of the motor platen relative to the wheel slide and thereby to vary the speed of the spindle so as to maintain a constant peripheral speed on the grinding wheel as it wears away.

5. In a grinding machine having a transversely movable wheel slide, a rotatable wheel spindle thereon, a grinding wheel on said spindle, a slidably mounted platen on said wheel slide, an electric motor on said platen, a variable speed multiple V-belt drive between said motor and wheel spindle including a multiple V-groove variable pitch automatic pulley on said motor, a multiple V-groove pulley on said spindle, multiple V -belts connected therebetween, means including a rotatable cam and a follower interposed between said platen and wheel slide to facilitate adjustment of said platen relative to the slide, a worm and warm gear mechanism to rotate said cam, a wheel truing apparatus on said slide including a longitudinally movable slide, a transversely movable carrier on said slide, a truing tool thereon, a nut and screw feeding mechanism including a rotatable nut interposed between said slide and carrier for feeding the truing tool toward and from the grinding wheel, a flexible shaft, gearing connecting one end of said shaft to said rotatable nut, and gearing connecting the other end of said shaft with the worm and worm gear mechanism whereby actuation of the truing tool feeding mechanism automatically actuates said cam so as to adjust the motor platen relative to the wheel slide and thereby to vary the speed of the spindle so as to maintain a substantially constant peripheral speed of the grinding wheel as it wears away.

6. In a grinding machine, as claimed in claim 1 in combination with the parts and features therein specified of a hydraulically operated mechanism to return said electric motor and truing tool carrier to initial positions including a fluid motor on said wheel slide, means includgaged, means including apiston and cylinder on said slide operatively connected to actuate said clutch, said cylinder serving as a normally closed sequence valve to control the admission of fluid under pressure to the fluid motor after the clutch is engaged, and a manually controlled solenoid valve to control the admission of fluid under pressure to said cylinder to engage said clutch and thereafter to start said fluid motor.

7. In a grinding machine, as claimed in claim 2, in combination with the-parts and features therein specified of a hydraulically operated mechanism to return said electric motor and truing tool carrier to initial positions including a fluid motor on said slide, means including a normally inoperative clutch on said slide operatively connected to rotate said cam in the reverse direction when engaged, means including a piston and cylinder on said slide operatively connected to actuate said clutch, said cylinder serving as a normally closed sequence valve to admit fluid to said fluid motor after the clutch is engaged, a manually controlled solenoid valve to control the admission of fluid under pressure to said cylinder to engage said clutch and thereafter to start said fluid motor, and means including a normally closed limit switch on said wheel slide havin an actuating plunger in alignment with said platen which is actuated by the rearwardmovement of the platen to deenergize said solenoid valve to disengage said clutch and to stop said fluid motor when the platen reaches its initial or rearward position.

8. In a grinding machine, as claimed in claim 2, in combination with the parts and features mechanism to return said electric motor and truing tool carrier to initial positions including a fluid motor on saidwheel slide, mean including a normally inoperative clutch on said wheel slide operatively connected to actuate said cam mechanism in the reverse direction when engaged, means including a piston and cylinder on said slide operatively connected to actuate said clutch, said cylinder serving as a normally closed sequence valve to control the admission of fluid under pressure to the fluid motor after the clutch is engaged, a manually controlled solenoid valve to control the admission of fluid under pressure to said cylinder to engage said clutch and thereafter to start said fluid motor, and means including an adjustable screw on said platen which is arranged to engage and move said piston rod rearwardly as the platen approaches its initial position so as to gradually cut-off the flow of fluid under pressure to said fluid motor to slowdown the rearward movement of said electric motor before'the clutch is disengaged to stop the rearward movement of the electric motor in its initial position.

References Cited in the file of this patent UNITED STATES PATENTS 

